c240 w202 engine cutting out

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New Member
Apr 29, 2007
Mercedes C240 Sport
Hi guys and gals,

It started last week - the car would be fine, but i'd get a small indication through the throttle (with no power) that car was about to cut out - 3 seconds later the car cut out.

The engine would die and all lights come up on the dash.

I would try to turn the car over, it would fire rev to 900rpm, die

This would happen a number of times (sometimes as many as 10) and then finally turn over, and purr sweet as a kitten.

I would remove the key - lock the car - unlock start and not every time but sometimes would turn over straight away.

On occasions under load (2.5k) it would die and come to a stop.

I had a look under the bonnet and found a earth cable broken on the near side - repaired thinking that was it but it only seems to have got worse - cutting out more often.

I thought it was the battery (8mth old from merc) this has been tested and found to be ok. i wondered if they were senative to voltage due to having the amp, phone and snooper plugged in - but switching this all off, it still happened.

I was wondering if anyone had any ideas what it may be!!

Its been a cracking car, good condition and a head turner so i would like to rectify it.

I thank you all in advance...

Cutting out when hot and not re-starting until it's cooled down is a classic sympton of crank sensor issues,

Not quite the same as you describe, but do you issues only occur when hot? If so worth a look.

How many miles - these typically seem to go @ around 100K
It tends to happen more if the car has been driven for about 25 mins..

the vehicle has done 183k ;) but looks more like 83 k

so the crank sensor - how cheap and difficult is it to replace?

Cheers guys
It sometimes when starting takes a long time to crank over (or it turns over itself) - switch it off - turn it over again and she'll fire start and run perfect.

Recently (what the thread was about) I can hear a buzzing/relay noise which appears to be on the passenger side above the air bag house.

Someone has suggested the immobilizer cutting in or a fault with the key/ barrel???

thanks for your help :)
cheers Olly :)
mmm still there - just not as bad

Right guys & girls - i have changed the crank sensor..car started took it for a run and all seemed ok...

However on load (around 4k) it seems to take ages to rev past - it then loses power, drops off, back on with the power, drops off.

At this point i let the throttle drop off and its ok...then it (sometimes) just cuts out.

This seems to happen after the engine is warmed up - 80/90 degrees....

Any further ideas??? - fuel pump etc?

Thanks in advance

get a star test done on her fastest way to get an answer
FUEL FILTER- how long ago was it changed?
fuel filter was changed last sept....however i did have a few problems with the garage that fitted it and the replacement pipe...i.e. it wasnt correct fuel pipe :(
Other possibility might be a problem with the electronic throttle either at pedal/sender end--[there's a small lever/cable I believe] or at the actuator end.

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